Pneumatic and hydraulically-operated tools are supplied with pressurized medium from compressors and pumps through flexible hose. The hose system includes a coupling having connectable and disconnectable parts for selectively connecting the tool to the compressor or pump.
At least one of the coupling parts or halves usually includes an axially displaceable valve which is engaged by a probe on the other coupling half which opens the valve during connection of the halves permitting flow through the coupling.
Normally, pressurized medium exists within the valved coupling half and the exposure of valve surfaces transverse to the valve axis of movement to this internal pressure imposes a high axial biasing force on the valve toward the closed position. Thus, very high axial forces must be applied to the coupling halves during connection in order to displace the valve against the pressurized medium forces imposed thereon. In systems having pressurized medium as high as 5000 psi, the forces necessary to achieve coupling connection may be so high that the system must be bled piror to the coupling parts being interconnected.
It is an object of the invention to provide a connectagainst-pressure coupling employing a valve wherein influence of the pressurized medium on the valve toward the closed position is minimal.
A further object of the invention is to provide a connectagainst-pressure coupling for high pressure systems utilizing an axially displaceable valve wherein the valve area exposed to the pressurized medium can be accurately regulated and controlled to prevent excessive axial valve opening forces being required during coupling interconnection of the parts.
Yet an additional object of the present invention is to provide a connect-against-pressure coupling for pressurized systems utilizing an axially displaceable valve wherein axial forces imposed upon the valve toward the closed position are minimized, the construction is economical and readily achieved with conventional machining processes, and bleed means are provided to permit valve operation even in the event of internal hydraulic leakage.
A coupling part in accord with the invention includes a tubular body having an axial passage extending therethrough. One end of the body is connectable to a hose, conduit, or the like, while the other end of the body comprises a connection end for mating with a complementary shaped coupling part. An axially displaceable tubular valve is located within the body passage and includes a valve head engagable with a valve seat defined in the passage for sealing the passage when the valve is in the closed position and a spring biases the valve toward the closed position.
A guide for the innermost part of the valve is fixed within the body passage receiving the innermost portion of the valve and guiding the valve during its axial displacement between open and closed positions. In accord with the invention the guide takes the form of an open-ended shell receiving the valve skirt, and an annular seal is interposed between the shell and valve skirt adjacent the shell open end preventing those portions of the valve inner end of a diameter less than that of the skirt from being exposed to the pressurized medium within the body passage. Ann annular pressure face transverse to the valve length is defined on the head of the valve adjacent the valve seat, and accordingly, the axial force imposed on the valve toward its closed position by the internal pressurized medium is controlled by the area of such transverse face.
The shell is provided with a unidirectional or check bleed valve permitting hydraulic pressurized medium which may have leaked into the shell and valve to escape upon the valve being displaced toward its open position in order to insure proper valve operating during the coupling connection. The bleed valve communicates with the body passage, and its valve element prevents the pressure within the passage from entering the shell and valve.
The practice of the invention minimizes the number of components as compared to known connect-against-pressure balanced couplings and as the shell is bled into the pressurized system no oil leakage to the atmosphere or exterior of the coupling occurs.